Field of the Invention
The present invention relates to a nanocrystal film-coated substrate, a manufacturing method of the same, and a manufacturing method of a barium zirconate titanate nanocrystal.
Description of Related Art
Barium titanate (BaTiO3) is known as a ferroelectric material. Barium titanate is used in a multilayer capacitor and the like because of high relative permittivity. Regarding barium zirconate titanate (Ba(Zr,Ti)O3) which is a solid solution of barium titanate (BaTiO3) and barium zirconate (BaZrO3), the followings are reported. In particular, in a composition in which a ratio of zirconium:titanium is in the vicinity of 20:80, integration, that is, pinching of phase transition temperatures (rhombohedron phase→orthorhombus phase→tetragon phase→cube phase) of barium titanate causes temperature dependency of permittivity to be smoothed and causes the maximum value thereof to be shown in the vicinity of room temperature.
Size reduction, capacity enlargement, and high reliability of a multilayer capacitor are progressing with recent miniaturization of electronic devices. In such a situation, there are various requirements for forms and particle diameters of dielectric particles to be used. A barium zirconate titanate nanocrystal is a very interesting material in a point that the barium zirconate titanate nanocrystal has monodispersity, is fine, and has a controlled hexahedral structure. In addition, it is possible to expect improvement of reliability for an operating temperature of a device and to expect an increase of permittivity in the vicinity of room temperature.
Regrading barium zirconate titanate, synthesis examples using methods such as a sintering method, a sonochemical method, a hydrothermal method, a coprecipitation method, or a sol-gel method are reported. For example, in the article of Non-Patent Literature 1, a method in which nanocrystals of barium zirconate titanate (Zr:Ti=20:80) are synthesized under a hydrothermal condition of a temperature of 130° C. by using a peroxo-hydroxide precursor is reported. In the article of Non-Patent Literature 2, a method in which nanocrystals of barium zirconate titanate (10 mol % to 30 mol % which is the substituted Zr content) are synthesized by a coprecipitation method is reported.